Department of Molecular Structures
Research
The Department of Molecular Structures conducts synchrotron-based research, offering a robust toolkit for scientists investigating materials containing actinides and lanthanides.
Experiments take place at the Rossendorf Beamline of The European Synchrotron (ESRF), in Grenoble (France) which is specifically dedicated to the actinide science and research on radioactive waste disposal. The beamline consists of four experimental stations -XAFS, XES, XRD-1, XRD-2:
- XAFS station with fluorescence and transmission detection for X-ray Absorption Fine-Structure (XAFS) spectroscopy, including (conventional) X-ray Absorption Near-Edge Structure (XANES) and Extended X-ray absorption fine-structure (EXAFS) spectroscopies
- XES with a 5-crystal Johann-type spectrometer for high-energy-resolution fluorescence-detection X-ray absorption near-edge spectroscopy (HERFD-XANES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS) measurements.
- XRD-1 station with a heavy-duty, Eulerian cradle, 6-circle goniometer for (high-resolution) powder X-ray diffraction (PXRD), surface-sensitive crystal truncation rod (CTR) and resonant anomalous X-ray reflectivity (RAXR) measurements
- XRD-2 station with a Pilatus3 x2M detector stage for single crystal X-ray diffraction (SCXRD) and in situ/in-operando PXRD measurements.
Our research provides detailed insights into the structural and electronic properties of actinide and lanthanide-containing materials across various scientific disciplines, including physics, chemistry, environmental science, and geoscience. We study fundamental electron interactions, bonding properties, probing the local structures and oxidation states of complex systems. Data analysis is performed with the help of electronic structure calculations.
EXAFS, HERFD-XANES, XES and RIXS is not restricted to crystalline solids, but can be applied to a wide range of samples, to derive information on e.g. aqueous speciation, complexation with dissolved inorganic ligands like chloride, sulfate or nitrate, complexation with organic ligands like acetate or humic acid, interaction with bacteria and plants, sorption to mineral and rock surfaces for actinides an other metals and metalloids. Due to the high penetration depth of the employed hard X-rays, the methods are suited to study chemical reactions in-situ/in-operando, for instance at very low or high temperatures, under special atmospheres, or under electrochemical potentials.
More about Rossendorf Beamline
Latest publication
Exploring metastable phases in cerium-doped zirconia: Insights from X-ray diffraction, Raman and Luminescence spectroscopy
Braga Ferreira dos Santos, L.; Svitlyk, V.; Richter, S.; Hennig, C.; Müller, K.; Bazarkina, E.; Kvashnina, K.; Stumpf, T.; Huittinen, N. M.
Abstract
The ZrO2-CeO2 system is crucial for various applications, but discrepancies persist regarding the miscibility of the cations and the occurrence of metastable phases in the Zr1-xCexO2 phase diagram. This work aimed to close these knowledge gaps by conducting detailed investigations of Zr1-xCexO2 compositions with varying cerium concentrations and incorporating Eu3+ as a luminescent probe. Synchrotron powder X-ray diffraction analysis revealed a miscibility gap between 20 and 50 mol% cerium, where two stoichiometric Zro.80Ce0.20O2 and Zro.50Ceo.50O2 phases coexist. Outside of this miscibility gap, solid solutions were found and various crystalline phases were identified, including monoclinic (m), tetragonal (t), tetragonal prime (t’), tetragonal double prime (t’’), and cubic (c), depending on the cerium concentration. The existence of the t’ and t’’ phases was confirmed through normalized lattice parameter an, and z(O) coordinates. Raman investigations revealed a distinct distortion band in all compositions containing the t’ phase. Contrary to existing literature, the HERFD-XANES demonstrated that the presence of the feature associated with distortion in Raman spectroscopy is not related to Ce3+, but is likely a result of the oxygen displacement in the t’ structure. Finally, luminescence spectroscopy of the europium environment in the samples revealed distinct excitation and emission spectra across the various crystal phases, enabling the unambiguous distinction of the metastable phases for the first time. This study reveals the complex binary ZrO2-CeO2 system, with several structural polymorphs. The ability to precisely control the phase composition offers immense potential for tuning the properties for different applications, such as in the SOFCs fields.
Keywords: ZrO2-CeO2 solid solutions; miscibility gap; D-band; tetragonal metastable phase; relative symmetry
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 40057) publication
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Journal of the American Chemical Society 64(2025)19, 9670-9683
DOI: 10.1021/acs.inorgchem.5c00865
Permalink: https://www.hzdr.de/publications/Publ-40057
Team
Head | |||||
Name | Bld./Office | +49 351 260 | |||
---|---|---|---|---|---|
Prof. Dr. Kristina Kvashnina | ROBL/21.6.04 | +33 476 88 2367 | |||
Employees | |||||
Name | Bld./Office | +49 351 260 | |||
Dr. Lucia Amidani | ROBL/14.1.04 | +33 476 88 1982 | |||
Dr. Nils Baumann | ROBL/21.6.03 | +33 476 88 2849 | |||
Clara Lisa E Silva | ROBL/14.1.04 | +33 476 88 2044 | |||
Jörg Exner | ROBL/BM20 | +33 476 88 2372 | |||
Dr. Christoph Hennig | ROBL/21.6.02a | +33 476 88 2005 | |||
Dr. Eleanor Sophia Lawrence Bright | +33 476 88 2462 | ||||
Dr. Damien Prieur | ROBL/21.6.03 | +33 476 88 2463 | |||
Dr. André Roßberg | 801/P316 | 2758 | |||
Anne Thielen | a.thielen![]() | ||||
Dr. Sami Juhani Vasala | s.vasala![]() |